This proposal is to study the patterns of expression of proto-oncogenes during the in vitro differentiation of mouse teratocarcinoma cells, and the development of mouse embryos, and their phenotypic effects on these systems. Expression of several proto-oncogenes has been found to change in some cell lines as the cells proliferate and go through the cell cycle, or as they differentiate. We will identify time and tissue specific expression of proto-oncogenes using in situ hybridization and whole mouse section hybridization techniques. The long term goals are to understand the regulation of these genes and whether they are necessary for differentiative changes. Specifically, we will introduce plasmids and retroviral vectors containing anti-sense sequences to down regulate expression in embryonal carcinoma cells and embryos. Vectors including proto-oncogene sequences linked to inducible promoters will also be used to study the effects of consistently high levels of transcription. During Phase I, I will take a core sequence of courses at Duke University. This proposal is health related because proto-oncogenes have been conserved through metazoan evolution, so they likely have essential functions in human growth and development. The major scientific disciplines involved are Genetics, Molecular Biology, Oncology, and Developmental Biology.